docs: def __correspond(self, ticket_id, text='', action='correspond', cc='', bcc='', content_type='text/plain', files=[]):
          """ Sends out the correspondence
  
          :param ticket_id: ID of ticket to which message belongs
          :keyword text: Content of email message
          :keyword action: correspond or comment
          :keyword content_type: Content type of email message, default to text/plain
          :keyword cc: Carbon copy just for this reply
          :keyword bcc: Blind carbon copy just for this reply
          :keyword files: Files to attach as multipart/form-data
                          List of 2/3 tuples: (filename, file-like object, [content type])
          :returns: ``True``
                        Operation was successful
                    ``False``
                        Sending failed (status code != 200)
          :raises BadRequest: When ticket does not exist
          """
          post_data = {'content': """id: {}
  Action: {}
  Text: {}
  Cc: {}
  Bcc: {}
  Content-Type: {}""".format(str(ticket_id), action, re.sub(r'\n', r'\n      ', text), cc, bcc, content_type)}
          for file_info in files:
              post_data['content'] += "\nAttachment: {}".format(file_info[0], )
          msg = self.__request('ticket/{}/comment'.format(str(ticket_id), ),
                               post_data=post_data, files=files)
          return self.__get_status_code(msg) == 200